A nightmare is a disturbing dream associated with negative feelings, such as anxiety or fear. Nightmares are common, and occasional nightmares usually are nothing to worry about. However, they may become a problem if you have them often and they disrupt your sleep or cause you to fear going to sleep. A diagnosis of nightmare disorder is only made if nightmares cause ongoing distress or problems with daytime functioning.

Nightmares may begin in children between 3 and 6 years old and tend to decrease after about age 10. Until age 13, boys and girls appear to have nightmares in equal numbers. At age 13, nightmares seem to be more prevalent in girls than boys. Some people have them as teens or adults or throughout their lives.

Nightmare disorder is referred to by doctors as a parasomnia — a type of sleep disorder that involves undesirable experiences that occur while you're falling asleep, during sleep or when you're waking up. Nightmares usually occur during the stage of sleep known as rapid eye movement (REM).

You normally go through four to six sleep cycles a night, cycling through the sleep stages in about 90 minutes. Your REM stage lengthens with each cycle, from several minutes in the first cycle to up to an hour in the last. You're more likely to have a nightmare in the second half to the last third of your night.

A nightmare may involve these features:

Your dream seems vivid and real, often becoming more disturbing as the dream unfolds

Your dream storyline is usually related to threats to your safety or survival

Your dream wakes you

You feel scared, anxious, angry, sad or disgusted as a result of your dream

You feel sweaty or have a pounding heartbeat, but do not leave the bed

You can think clearly upon awakening and can recall details of your dream

Your dream occurs near the end of your sleep time

Your dream keeps you from falling back to sleep easily

You may have nightmare disorder if, in addition to the above:

The sleep disturbance causes significant distress or problems with functioning during the day

Medications or physical or mental disorders do not adequately explain the fact that you have nightmares

Children's nightmare content varies with age, typically becoming more complex. While a young child might dream of monsters, an older child might have nightmares about school or difficulties at home.

When to see a doctor

Occasional nightmares aren't usually a cause for concern. If your child has nightmares, you can simply mention them at a routine well-child exam.

Talk to your doctor sooner if nightmares:

Occur frequently and persist over time

Routinely disrupt sleep

Cause fear of going to sleep

Cause daytime behavior problems

Nightmares are only considered a disorder if disturbing dreams cause you distress or keep you from getting enough sleep. Nightmares can be triggered by many factors, including:

Stress. Sometimes the ordinary stresses of daily life, such as a problem at home or school, trigger nightmares. A major change, such as a move or the death of a loved one, can have the same effect.

Trauma. Nightmares are common after an accident, injury or other traumatic event. Nightmares are prominent in post-traumatic stress disorder (PTSD).

Sleep deprivation. Changes in your schedule that cause irregular sleeping and waking times or that interrupt or reduce the amount of sleep can increase your risk of having nightmares.

Medications. Some drugs — including certain antidepressants, blood pressure medications, beta blockers, and drugs used to treat Parkinson's disease or to help you stop smoking — can trigger nightmares.

Substance abuse. Alcohol and illegal drug use or withdrawal can trigger nightmares.

Scary books and movies. Reading scary books or watching scary movies, especially before bed, can be associated with nightmares.

Other disorders. Some medical conditions and mental health disorders as well as other sleep disorders can be associated with having nightmares. For instance, anxiety can be associated with a higher likelihood of recurrent nightmares.

Nightmare disorder may cause:

Excessive daytime sleepiness, which can lead to difficulties at school or work, or problems with everyday tasks, such as driving and concentrating

Problems with mood, if the anxiety from the dream continues to bother you

Resistance to going to bed or to sleep for fear you'll have another bad dream

For children, nightmares tend to decrease by the time they're teenagers. However, if you have concerns about safety or underlying conditions, you may want to see your doctor. Your doctor may refer you to a sleep specialist.

It's a good idea to prepare for your appointment. Here's some information to help you.

What you can do

Keep a sleep diary for two weeks before your appointment to help your doctor understand your or your child's sleeping pattern. In the morning, record as much as you know of the bedtime ritual, quality of sleep and so on. At the end of the day, record behaviors that may affect sleep, such as caffeine consumption or medications taken.

List all medications, vitamins or other supplements you're taking and the dosages.

List any symptoms you're experiencing, including any that may seem unrelated to the reason for the appointment.

Note key personal information, including any major stresses or recent life changes.

Bring a family member or friend along, if possible, to help you remember what the doctor says.

List questions to ask your doctor to make the most of your time together.

Some basic questions to ask your doctor include:

What is likely causing my symptoms or condition?

What are other possible causes?

What kinds of tests do I need?

Is my condition likely temporary or chronic?

What is the best course of action?

What are the alternatives to the primary approach you're suggesting?

Are there any restrictions that I need to follow?

Should I see a specialist?

Are there any brochures or other printed material that I can have? What websites do you recommend?

Don't hesitate to ask other questions that occur to you.

What to expect from your doctor

Your doctor is likely to ask you several questions, including:

When did you begin experiencing symptoms?

How often do the nightmares occur, and what are they about?

What do you usually do before bedtime?

Have you had sleep problems in the past?

Does anyone else in your family have sleep problems?

There are no tests routinely done to diagnose nightmare disorder. Recurrent nightmares can sometimes indicate underlying anxiety. If that's likely, the doctor may refer the child to a psychologist for assessment and management.

Nightmare disorder should be distinguished from:

Sleep terrors, a different parasomnia in which you're likely to sit up, scream, talk, thrash and kick

Occasionally, if your sleep is severely disturbed, your doctor may recommend an overnight sleep study to help determine if the nightmares are connected to another sleep disorder.

Sleep studies

A sleep study (polysomnography) is a test used to diagnose sleep disorders and typically requires that you spend the night in a sleep lab. During the test, sensors are placed on your head and body to record your brain waves, the oxygen level in your blood, heart rate and breathing, as well as eye and leg movements. In some studies, a video camera will record your sleep.

Your doctor will review the information to determine whether you have any sleep disorders.

Treatment for nightmares isn't usually necessary. If the nightmares are causing you distress and interfering with your daytime functioning, talk to your doctor. The cause of the nightmare disorder helps determine treatment.

Medical condition treatment. If the nightmares are associated with an underlying medical or mental health condition, treatment is aimed at the underlying problem.

Stress or anxiety treatment. If stress or anxiety seems to be contributing to the nightmares, your doctor may suggest stress-reduction techniques, counseling or therapy.

Medication. Medication is rarely used to treat nightmares. However, medications that reduce REM sleep or reduce awakenings during sleep may be recommended if you have severe sleep disturbance.

Imagery rehearsal therapy. Often used with people who have nightmares as a result of PTSD, imagery rehearsal therapy involves changing the ending to your remembered nightmare while awake so that it's no longer threatening. You then rehearse the new ending in your mind. This approach may decrease the frequency of nightmares.

If you're having nightmares, try some relaxation techniques before bedtime. Take a warm bath, meditate or practice deep breathing. A consistent bedtime routine is important. If your child is struggling with nightmares, be patient, calm and reassuring. Sometimes a little creativity helps, too.

Offering comfort. After your child awakens from a nightmare, respond quickly and soothe your child at the bedside. This may prevent future nightmares.

Talk about the dream. Ask your child to describe the nightmare. What happened? Who was in the dream? What made it scary? Then remind your child that nightmares aren't real and can't hurt you.

Put stress in its place. If your child seems anxious or stressed, talk about what's bothering him or her. Practice some simple stress-relief activities, such as deep breathing.

Rewrite the ending. As in imagery rehearsal therapy, help your child imagine a happy ending for the nightmare. Encourage your child to draw a picture of the nightmare, "talk" to the characters in the nightmare or write about the nightmare in a journal.

Provide company. Your child might feel more secure if he or she sleeps with a favorite stuffed animal, blanket or other comfort object.

Brighten up. Use a night light in your child's room. If your child wakes up during the night, the light might be reassuring.

Open the doors. Leave your child's door open at night so that he or she won't feel alone. Leave your door open, too, in case your child needs comfort during the night.

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